Fruit maturity: correct harvest date is important as overmature fruit are more prone to damage and rotting.
Handling: poor handling of fruit at harvest increases the risk of wound fungi such as Botrytis, Penicillium and Mucor.
Mineral composition: fruit low in calcium and high in potassium and nitrogen are more prone to rots particularly Gloeosporium in Cox. Therefore, correct mineral composition is important for varieties such as Cox and Bramley.
Weather: rainfall is the most critical factor in determining infection of apples by fungi. Wet summers and harvests usually result in high rot incidence in store.
Storage rots (orchard diseases)
| Disease | Varieties | Source | Entry | Weather factors | Cultural control | Fungicides |
|---|---|---|---|---|---|---|
| Black rot (Botryosphaeria obtusa) See images below | Cox, Fiesta + others | Cankers, mummified fruit, dead twigs, prunings, weeds | Direct and wounds | Warm (20oC) +rain, humid |
Prune out cankers and dead wood Remove/collect mummies Avoid piles of prunings in orchard |
At present not important enough to require special measures |
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| Botryosphaeria rot on apple fruit in orchard showing characteristic concentric zones of rot growth | Botryosphaeria rot around calyx end of Cox apple, associated with insect damage | Botryosphaeria rot at eye end of Cox apple after CA storage, showing characteristic purple colour |
Storage rots (orchard diseases) contd.
| Disease | Varieties | Source | Entry | Weather factors | Cultural control | Fungicides |
|---|---|---|---|---|---|---|
| Botrytis eye and core rot (Botrytis cinerea) | Cox | Ubiquitous especially dead plant material, eg. flowers | Direct from dead petals to eye or to core. May require mature fruit to rot | Humid or wet | None | Possibly sprays during blossom |
| Brown rot (Monolinia fructigena) | All varieties | Cankers, mummified fruit on orchard floor and tree | Initially by wounds. Spread by contact | Warm summer + rain |
Prune out cankers Remove/collect mummies Good control of P&D Avoid fruit damage Close supervision of pickers to ensure no damaged fruit is stored |
Pre-harvest spray depending on risk |
|
Diaporthe rot (Diaporthe perniciosa) See image below |
Cox, Bramley, Jonagold, Gala | Cankers, dead wood, mummies | Direct on mature fruit long-term stored | Warm and wet | Remove cankers, dead and weak wood during pruning | Rot usually not important enough to merit special control measures |
Diaporthe rot on Cox
Storage rots (orchard diseases) contd.
| Disease | Varieties | Source | Entry | Weather factors | Cultural control | Fungicides |
|---|---|---|---|---|---|---|
| Fusarium rot (Fusarium spp) | Cox, Bramley, Cameo | Orchard soil, plant debris, cankers, dirty bulk bins |
Wounds Core rot |
Rain, warm weather | Prune out old Nectria cankers and pruning snags | Usually not important enough to merit special attention on most varieties. On Bramley and Cameo, apply fungicide sprays at blossom and petal fall |
| Gloeosporium rot (Neofabraea spp.) | Cox, Gala, Jonagold, Egremont Russet | Cankers, pruning snags, mummified fruits | Direct, through lenticels, eye, stalk, russet cracks | Warm weather + rain |
Prune out cankers, dead stubs and die-backs Remove mummies |
Pre-harvest sprays July - September |
| Nectria rot (Neonectria ditissima) | Cox, Bramley, Gala, Egremont Russet | Cankers | Direct through lenticels, stalk end, eye end | Wet autumn at leaf fall. Wet spring, summer | Removing cankers and macerate with prunings |
Post-harvest copper sprays to protect leaf scar, sprays at bloom and petal fall Post-harvest sprays |
|
Phytophthora rot (Phytophthora syringae) |
All varieties | Soil splash | Direct entry, spread by contact | Wet especially near picking |
Maximum width grass strip Mulching to cover soil to reduce soil splash Removing low hanging branches Selective picking Not muddying bulk bins Encouraging earthworms to remove leaf litter |
Post-harvest urea to trees to encourage leaf rot when fall Pre-harvest sprays |
Storage rots (store diseases)
| Disease | Varieties | Source | Entry | Weather factors | Cultural control | Fungicides |
|---|---|---|---|---|---|---|
| Blue mould (Penicillium expansum) | All varieties especially Bramley | Plant debris, orchard soil, dirty bulk bins | Wounds, direct entry on over-mature fruit | Store disease |
Careful picking and handling to avoid damage Good control of pest and disease Avoid muddying bins and introducing debris such as leaves Clean bulk bins |
Post harvest dips/drenches aggravate the problem |
| Botrytis rot (Botrytis cinerea) | All varieties | Plant debris, orchard soil, dirty bulk bins |
Wounds Infected stems |
Store disease rapid growth at low temperatures |
Careful picking to avoid wounds Good control of pest and disease Avoid muddying bulk bins and introducing debris such as leaves Clean bulk bins |
Pre-harvest sprays may give some control |
| Mucor rot (Mucor Spp) | All varieties | Orchard soil, dirty bulk bins | Wounds or through open eye in drench solution |
Store disease rapid growth at low temperatures Wet harvesting |
Avoid muddying bins and introducing debris Clean bulk bins Removing fallen fruit from orchard after harvest to reduce fungus population in soil Store dry fruit |
No fungicides are effective against Mucor Post-harvest dips/drenches aggravate the problem |